The present invention relates generally to apparatuses for cleaning grain and more particularly to gravity-fed apparatuses employing screens without having external vibrating means.
The notion of separating fines from clean grain by gravity feeding the material to be screened through a zig-zag path with the underside of each zig and each zag being a screen has long been recognized in the art, as is evidenced, for example, by U.S. Pat. Nos. 1,168,282; 1,173,249; 1,185,595; 1,945,242; and 2,203,152. While generally satisfactorily accomplishing their goal without the need for moving parts and accompanying machinery, such screeners had the common disadvantage of shortly becoming clogged with material such as broken pieces of grain without affording efficient and simple access to their interiors for cleaning, replacing screens and general maintenance. Hence, other configurations of screens which are mechanically vibrated or powered rotary screeners which tumble the material to be screened are frequently employed. By maintaining the grain or other material to be screened in a constant state of agitation, the clogging tendency is greatly reduced. While screens thus employed do not clog as quickly, a more complex and expensive piece of equipment is required, the separating action is less efficient and screen replacement is still somewhat difficult.
A rather popular type of gravity feeder which offers a solution to the screen cleaning and replacement dilemma, is in the form of a large gem having a silhouette in the shape of a diamond. The bottom half of the diamond is in the form of a large funnel having a square cross-section. The upper half of the diamond is identically shaped, but inverted, and has a smaller similarly shaped structure of screen material within it which is spaced away from its inner surfaces. This screen structure is connected at its bottom to a smaller solid walled lower half of what completes an interior diamond-silhouette structure, the bottom half of which is also spaced away from the bottom half of the exterior diamond-silhouette structure. The inverted funnel shaped screen is not open at its top and when grain enters at the top of the larger exterior structure, fines passing through the screen are caught by the interior lower solid wall structure and discharged through its bottom. Clean grain travels between the interior diamond-silhouette structure and the exterior diamond-silhouette structure through a discharge in the bottom thereof.
Such gravity-fed cleaners typically have, at their mid-sections, a square cross-section with sides 10 feet or longer in length. The smaller more compact gravity fed grain cleaners of the zig-zag chute type handle equivalent flow rates to those of the large diamond-silhouette type, primarily due to the increased agitation of the grain each time its flow path is abruptly altered by 90.degree.. However, the diamond-silhouette type of gravity-fed grain cleaner is, of necessity, large enough a size that access to its interior structures for cleaning and replacing screens does not present a nearly impossible situation.
Nevertheless, a great deal more screen material and casing material is required to build the diamond-silhouette style grain cleaner than would be for prior art zig-zag cleaners and replacing screens is generally still a two man job requiring several hours of difficult labor. The present invention provides a cleaner which is materially more efficient than prior art zig-zag cleaners and, at the same time allows access for rapid screen replacement.